This invention relates generally to the repair of gas turbine engine components and more particularly to methods of attaching a repair section to a portion of an existing turbine component.
A gas turbine engine includes a compressor that provides pressurized air to a combustor wherein the air is mixed with fuel and ignited for generating hot combustion gases. These gases flow downstream to a turbine section that extracts energy therefrom to power the compressor and provide useful work such as powering an aircraft in flight.
During operation, turbine components, in particular the airfoils in the compressor, are exposed to a high velocity air stream that can lead to oxidation, corrosion, physical damage, and cracking from thermal cycling. Because turbine components are complex in design, are made of relatively expensive materials, and are expensive to manufacture, it is generally desirable to repair them whenever possible.
One known repair method involves providing a repair section (sometimes referred to as a “SPAD”. which duplicates a portion of the airfoil. Damaged portions of the field-used airfoils are cut off and then the SPAD is welded or otherwise bonded in place.
Accurate and secure placement of the SPAD during the welding process is necessary to produce a satisfactory end product. The repair requires alignment of the leading and trailing edges as well as circumferential, axial and twist positions. The ability to maintain accurate orientation in a robust welding environment demands a preliminary fixture provide a stable assembly of the components in an equally robust assembly.
Prior art attempts to use this welding technique for 3D airfoil shapes have resulted in poorly aligned leading and trailing edges as well as misalignment in the stacking axis and twist orientation. Further attempts to correct alignment have indicated the lack of current technology to assure alignment.
Accordingly, there is a need for a method of repairing turbine components using a repair section or SPAD while maintaining precise alignment.